Battle of Tismanum

The Battle of Tismanum was fought in 271 AD during the Crisis of the Third Century. The Roman Legio IV Pannonica was attacked by the army of the Buri king Sigimund as it marched to recapture the Dacian provincial capital of Zarmizegetusa, but Pacuvius Atronius led his army to victory against all odds and slew Sigimund as he retreated with his army. The victory at Tismanum vanquished the Buri threat, and Zarmizegetusa was recaptured shortly after.

Background
In 270 AD, the Germanic tribes took advantage of the Roman Empire's political instability to pour into Rome's frontier provinces, namely Dacia and Pannonia. Among these tribes were the Buri and Quadi; in 271 AD, the Quadi conquered northern Pannonia with the sack of Aquincum, while the Buri conquered Zarmizegetusa from its brave Roman garrrison. The Roman Legio IV Pannonica, which had subdued its troublesome Roxolani neighbors, was redeployed to reconquer Zarmizegetusa and Aquincum. The 1,400-strong Legio IV Pannonica was sent from Drobeta in the south to recapture Zarmizegetusa from the Buri, but the overconfident Buri king Sigimund led his army over 2,400 warriors south to attack the Roman legion as it marched north. The two armies met halfway between Drobeta and Zarmizegetusa near present-day Tismana in lower Wallachia, Romania, back then known as "Tismanum".

Battle
The Roman legion was smaller than the attacking Buri army, but Pacuvius decided to arrange his legion in a diagonal line, with his right flank extending towards the enemy, and his left flank sloping backwards. This tempted the Buri into attacking the exposed Roman right flank, throwing their whole army against it. The Romans then sprung their trap, having their left flank wheel around the Buri army and envelop their entire right flank. The Buri were slaughtered from two sides, and the Romans proceeded to move further along their line, decimating individual bands of their warriors and destroying them from two sides. The entire Buri army collapsed, and the Roman cavalry (including Germanic mercenaries) rode down the fleeing Buri warriors and even slew King Sigimund and several of his noble bodyguards. The Buri army was thoroughly destroyed, losing 86% of their total strength on the battlefield; the Romans killed their 210 prisoners.

Aftermath
The remnants of the Buri army were forced to retreat, having lost their king and suffered devastating casualties. The battle was a decisive Roman victory over the weakened Buri, and the Romans would soon deal with the invading Quadi army in Pannonia. Ultimately, the two weakened Germanic tribes merged into a confederation, but even this was unable to prevent their defeats at the hands of Rome.